Batteries with silicon anodes promise 20% longer life on a single charge.

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Gene Berdichevsky believes in batteries. As employee number seven at Tesla, he helmed the team that designed the lithium-ion battery pack for the company’s first car, the Roadster, which convinced the world to take electric vehicles seriously. A decade later, EVs can hold their own against your average gas guzzler, but there’s still a large trade-off between the shelf life of their batteries and the amount of energy packed into them. If we want to totally electrify our roads, Berdichevsky realized, it would require a fundamentally different approach.

In 2011, Berdichevsky founded Sila Nanotechnologies to build a better battery. His secret ingredient is nanoengineered particles of silicon, which can supercharge lithium-ion cells when they’re used as the battery’s negative electrode, or anode. Today, Sila is one of a handful of companies racing to bring lithium-silicon batteries out of the lab and into the real world, where they promise to open new frontiers of form and function in electronic devices ranging from earbuds to cars.

The long-term goal is high-energy EVs, but the first stop will be small devices. By this time next year, Berdichevsky plans to have the first lithium-silicon batteries in consumer electronics, which he says will make them last 20 percent longer per charge. As the lustrous feedstock for the digital hearts of most modern gadgets, silicon and lithium are a dynamic duo on par with Batman and Robin. Crack open your favorite portable device—be it a phone, laptop, or smartwatch—and you’ll find a lithium-ion battery eager to provide electrons, plus a silicon-soaked circuit board that routes them where they need to go. But if you combine the metals in a battery, it can create all sorts of problems.

When a lithium-ion battery is charging, lithium ions flow to the anode, which is typically made of a type of carbon called graphite. If you swap graphite for silicon, far more lithium ions can be stored in the anode, which increases the energy capacity of the battery. But packing all these lithium ions into the electrode causes it to swell like a balloon; in some cases, it can grow up to four times larger.

The swollen anode can pulverize the nanoengineered silicon particles and rupture the protective barrier between the anode and the battery’s electrolyte, which ferries the lithium ions between the electrodes. Over time, crud builds up at the boundary between the anode and electrolyte. This both blocks the efficient transfer of lithium ions and takes many of the ions out of service. It quickly kills any performance improvements the silicon anode provided.

One way out of this problem is to sprinkle small amounts of silicon oxide—better known as sand—throughout a graphite anode. This is what Tesla currently does with its batteries. Silicon oxide comes pre-puffed, so it reduces the stress on the anode from swelling during charging. But it also limits the amount of lithium that can be stored in the anode. Juicing a battery this way isn’t enough to produce double-digit performance gains, but it’s better than nothing.

Cary Hayner, cofounder and CTO of NanoGraf, thinks it’s possible to get the best of silicon and graphite without the loss of energy capacity from silicon oxide. At NanoGraf, he and his colleagues are boosting the energy of carbon-silicon batteries by embedding silicon particles in graphene, graphite’s Nobel Prize-winning cousin. Their design uses a graphene matrix to give silicon room to swell and to protect the anode from damaging reactions with the electrolyte. Hayner says a graphene-silicon anode can increase the amount of energy in a lithium-ion battery by up to 30 percent.

But to push that number into the 40 to 50 percent range, you have to take graphite completely out of the picture. Scientists have known how to make silicon anodes for years, but they have struggled to scale the advanced nanoengineering processes involved in manufacturing them.

Sila was one of the first companies to figure out how to mass-manufacture silicon nanoparticles. Their solution involves packing silicon nanoparticles into a rigid shell, which protects them from damaging interactions with the battery’s electrolyte. The inside of the shell is basically a silicon sponge, and its porosity means it can accommodate swelling when the battery is charging.

This is similar to the approach used by materials manufacturer Advano, which is producing silicon nanoparticles by the ton in its New Orleans factory. To lower the costs of producing nanoparticles, Advano sources its raw material from silicon wafer scrap from companies that make solar panels and other electronics. The Advano factory uses a chemical process to grind the wafers down into highly engineered nanoparticles that can be used for battery anodes.

“The real problem is not ‘Can we get a battery that is powerful?’ It’s ‘Can we make that battery cheap enough to build trillions of them?’” says Alexander Girau, Advano’s founder and CEO. With this scrap-to-anode pipeline, Girau believes he has a solution.

So far, none of these companies have seen their anode material used in a consumer product, but each is in talks with battery manufacturers to make it happen. Sila expects its anodes to be in unnamed wireless earbuds and smartwatches within a year. Advano, which counts iPod cocreator Tony Fadell among its investors, is also in talks to have its anodes placed in consumer electronics in the near future. It’s a long way from EVs, but proving the tech works in gadgets is a small step in that direction.

“The pace of battery development is not as fast as other technology areas, such as computing,” says Matthew McDowell, a materials scientist at the Georgia Institute of Technology. The reason, he says, has to do with the complex interplay of the variables involved when swapping out graphite for silicon in battery anodes. It’s not just a matter of increasing energy density, but also making sure that this doesn’t reduce the battery’s thermal stability, charge rate, or life span.

“Engineering new materials at scale that can improve capacity while satisfying all these other metrics is a major challenge,” McDowell says. “It’s not surprising that commercialization has taken a while.”

This is why companies are starting with small consumer electronics for the first wave of silicon-lithium batteries. They are the “low-hanging fruit,” says Laurence Hardwick, director of the Stephenson Institute for Renewable Energy. Batteries in gadgets only need to last for a few years. EVs require batteries that last more than a decade and can handle daily recharging, a wide range of temperatures, and other unique stressors. Hardwick says that building a lithium-silicon battery that retains its high energy over longer time spans is a “much greater challenge.”

Berdichevsky is well aware of the obstacles to the mass production of an EV-worthy lithium-silicon battery. He doesn’t expect to see silicon anodes in commercial EVs until at least the middle of the decade. But once they arrive, he believes, lithium-ion batteries will remake the auto industry—again.

However, the comment about the pace of battery technology is spot on. Something to be remembered is that the motor design used in EVs has been in use for over a century, and progressive refinement has in that time got the efficiency up from maybe 85% to maybe 95%. The "silicon revolution" happened in such a short timescale that we forget that such events are rare - for instance, the thermal efficiency of gasoline engines has gone from around 20% to around 40% in a century with most of the progress in the last half of that period. I suspect that at the moment EV adoption is entirely about two things: cost reduction of what we already have, and government commitment to the necessary infrastructure to cope with the limitations. A battery 40% lighter (which is initially what it means) is likely to be a vehicle weight improvement of only around 10-15%.

However, the comment about the pace of battery technology is spot on. Something to be remembered is that the motor design used in EVs has been in use for over a century, and progressive refinement has in that time got the efficiency up from maybe 85% to maybe 95%. The "silicon revolution" happened in such a short timescale that we forget that such events are rare - for instance, the thermal efficiency of gasoline engines has gone from around 20% to around 40% in a century with most of the progress in the last half of that period. I suspect that at the moment EV adoption is entirely about two things: cost reduction of what we already have, and government commitment to the necessary infrastructure to cope with the limitations. A battery 40% lighter (which is initially what it means) is likely to be a vehicle weight improvement of only around 10-15%.

Weight isn’t the blocker for automotive applications; cost is. 20% denser for the same cost means 20% more range for the same price car, or about 5% lower price.

I'm not going to hold my breath on this new tech actually hitting and becoming the revolution (or even evolution) necessary as I always take these kind of announcements with a grain of, well in this case, sand.

A few things they don't hit on is charge cycles. Like, cool they'll last a bit longer, but how many charge cycles can they withstand? Especially with the known problems of the anode they described? If they're expanding so much during the charge cycle and then contracting back to normal after (I assume as they didn't mention specifically), how long before these stressors break the anode or cause complications thereof?

That aside, what's the safety of these batteries compared to regular Li-Ion batteries? If they're storing more energy and thus, are more energy dense, that creates a much more dangerous scenario if they rupture, especially if, as one company states, the batteries are 50% or more dense. I wonder this as I often see iPads broken with their batteries expanded sitting in display kiosks are big box stores. The one closest to my house finally, after nearly 6 months, removed their two iPads from the display. their shells split in two as the battery tries desperately to escape.

Though, my main concern is the number of usable cycles the batteries can undergo before they're no longer useable.

And yet, the design of lithium ion batteries still has an unsolved problem. The batteries need to be designed to stop the buildup of their charge-cycle dendrites which end up shorting cells, degrading capacity, and ultimately require the batteries to be completely replaced (which is exactly the kind of wastefulness we need to get away from) or even rapid, uncontrolled discharges (ie explosions and fires). And this design does nothing about that problem.

Solve the dendrite problem first. Then worry about higher capacities or faster charging. Make batteries that can literally be used forever. There's no reason we should be making them any other way, and EVERY reason we should make them last. With 6.8 billion people in the world, and several billion vehicles, we need our EV batteries to NOT be a waste product and a massive power-sink to constantly replace them.

I'm not going to hold my breath on this new tech actually hitting and becoming the revolution (or even evolution) necessary as I always take these kind of announcements with a grain of, well in this case, sand.

A few things they don't hit on is charge cycles. Like, cool they'll last a bit longer, but how many charge cycles can they withstand? Especially with the known problems of the anode they described? If they're expanding so much during the charge cycle and then contracting back to normal after (I assume as they didn't mention specifically), how long before these stressors break the anode or cause complications thereof?

That aside, what's the safety of these batteries compared to regular Li-Ion batteries? If they're storing more energy and thus, are more energy dense, that creates a much more dangerous scenario if they rupture, especially if, as one company states, the batteries are 50% or more dense. I wonder this as I often see iPads broken with their batteries expanded sitting in display kiosks are big box stores. The one closest to my house finally, after nearly 6 months, removed their two iPads from the display. their shells split in two as the battery tries desperately to escape.

Though, my main concern is the number of usable cycles the batteries can undergo before they're no longer useable.

If you’re still waiting for a revolution, you always will be.

For longevity: starting at the third paragraph, that’s all this article is talking about.

Battery capacity is just part of story. Much bigger problem is charging and this could not be solved. For example 100kWh requires, at ideal conditions, 100kW for 1 hour, 200kW for 30 min... 1200kW (1.2MW!!!) for 5 min.If we accept long charging times (world will stop cause of this) energies are enormous! Home electric shower is 5 - 7kW, central heating 20 - 30kW and 1 hour charging 100kW! Continuously for single car!

Battery capacity is just part of story. Much bigger problem is charging and this could not be solved. For example 100kWh requires, at ideal conditions, 100kW for 1 hour, 200kW for 30 min... 1200kW (1.2MW!!!) for 5 min.If we accept long charging times (world will stop cause of this) energies are enormous! Home electric shower is 5 - 7kW, central heating 20 - 30kW and 1 hour charging 100kW! Continuously for single car!

Nonsense. The amount you need to charge at home is nothing to do with battery size, and everything to do with the amount of driving you do in a day. And charging overnight to replenish the day's usage is not an issue. At all. There are real infrastructure issues, such as multi unit buildings, and street parking, where access to charge points is an issue; but these are different, soluble problems, not requiring MW charging points. 5kW per point would do it, although more would be nice ( and not that difficult).

However, the comment about the pace of battery technology is spot on. Something to be remembered is that the motor design used in EVs has been in use for over a century, and progressive refinement has in that time got the efficiency up from maybe 85% to maybe 95%. The "silicon revolution" happened in such a short timescale that we forget that such events are rare - for instance, the thermal efficiency of gasoline engines has gone from around 20% to around 40% in a century with most of the progress in the last half of that period. I suspect that at the moment EV adoption is entirely about two things: cost reduction of what we already have, and government commitment to the necessary infrastructure to cope with the limitations. A battery 40% lighter (which is initially what it means) is likely to be a vehicle weight improvement of only around 10-15%.

One of the great enablers in modern electronics was the cheap and fast power transistors that became available during the 90's. Compare wall warts between 1990 and 2000, one is 200g of transformer, the other has a 10 gram transformer thanks to fast switching. Same thing with dcdc converters in cars and laptops, fancy motor controllers in cars and drones.

Many ev's use permanent magnet motors (bldc I guess they are called), (including the back motor in tesla model 3, front is induction, I think), Permanent magnet ac motors were made practical with modern power electronics, but even the traditional induction motor needs such power electronics in the controller to be reasonable to use in a modern car. I think reasonable dc motor pwm speed controllers were available a bit earlier (80's?).

Battery capacity is just part of story. Much bigger problem is charging and this could not be solved. For example 100kWh requires, at ideal conditions, 100kW for 1 hour, 200kW for 30 min... 1200kW (1.2MW!!!) for 5 min.If we accept long charging times (world will stop cause of this) energies are enormous! Home electric shower is 5 - 7kW, central heating 20 - 30kW and 1 hour charging 100kW! Continuously for single car!

Nonsense. The amount you need to charge at home is nothing to do with battery size, and everything to do with the amount of driving you do in a day. And charging overnight to replenish the day's usage is not an issue. At all. There are real infrastructure issues, such as multi unit buildings, and street parking, where access to charge points is an issue; but these are different, soluble problems, not requiring MW charging points. 5kW per point would do it, although more would be nice ( and not that difficult).

On top of that, if we could manage to get policy etc in order for people to slow-charge in the night and then sell say 5% of that when power usage jumps in the morning, the owner can use the difference in spot price to pay a little bit of the car and we get an enormous distributed peaker grid energy storage to smooth out the grid load and power generation needs. (The odd day you need full range, you just tell your car not to sell anything, just as you tell the car to charge full instead of 80% or whatever standard is).

I am currently working on my doctorate in battery research. Sila and Nanograf are definitely the Si-anode leaders. Silicon is definitely seen as the magic solution material, as long as we can prevent degradation from volume expansion. The C-shell method, however, is not perfect.

I'll have to check my data, but I think Nanograf has a patent on what they call the yolk-shell method, which is just having a large shell of graphite surrounding a Si-nanoparticle. However, there is a void within each 'reactor' which allows for the volume expansion. The issue here is that charge can only flow to the silicon through contact with the graphite. With the yolk shell design, there is a limitation for how much lithium can flow into each reactor.

These two companies are doing great work, but we still have a way to go before we see the silicon revolution that the battery industry is dying for.

It's been a while since my EE days, but I seem to remember the anode as the "sink" (+), and the cathode as the source (-).

edit2: damn, current directions can be confusing. The issue here I think is a different one: the battery expansion they are talking about is during charging, when the current is in the opposite direction of the discharge direction.

It's been a while since my EE days, but I seem to remember the anode as the "sink" (+), and the cathode as the source (-).

Depends when you were in school, as I was never exposed to that nomenclature in regards to batteries, but first saw it in circuit design in reference to transistors.

Furthermore, if you were taught 'conventional ' current circuit analysis, the anode is the positive electrode and the cathode is the negative. In 'electron' current convention, the anode is negative and the cathode is positive. Doesn't mattter which one you accept on paper, once you learn to design complex circuits and read schematics, it's like your first language.

Regardless of the materials, it seems like increasing the J/cm^3 of energy storage is going to increase the danger. There is a lot of energy in a gallon of gasoline, and it's dangerous in an accident, although car design evolution has helped. Packing more energy into a cubic cm of battery will also add danger, all things being equal. I guess my point is nothing comes free, and beware of "yay more energy". How much energy do we hope to hold in our (cellphone) hand?

We do allow thousands of semis on the roads daily, constantly shuffling thousands of gallons of gasoline back and forth between gas stations in your neighborhood and the refineries. At the car level, you can have an old classic Mini with a eight gallon tank next to a dual-tanked truck with forty or fifty gallons. It's all relative. That's all.

Battery capacity is just part of story. Much bigger problem is charging and this could not be solved. For example 100kWh requires, at ideal conditions, 100kW for 1 hour, 200kW for 30 min... 1200kW (1.2MW!!!) for 5 min.If we accept long charging times (world will stop cause of this) energies are enormous! Home electric shower is 5 - 7kW, central heating 20 - 30kW and 1 hour charging 100kW! Continuously for single car!

I thought the promise of an all electric future is that the car fills itself up every night. Thus the only times you will actually need to wait on it will be if you exceed it's range during a single day, so road trips. If you have it top off while you eat a meal, you are golden! You will end up spending less time at filling stations, not more.

Friend owns a Tesla. One thing he genuinely loves is never having to stop to fill up anymore. Plus his work provides free charging. He has put 40k miles on his Model 3! Yet averaged $5/mo in electricity costs for it. I'm not convinced the world would stop if it followed suit. Particularly considering most vehicles will be charging during off peak hours, and can be set to slow charge all night to save $$$.

Regardless of the materials, it seems like increasing the J/cm^3 of energy storage is going to increase the danger. There is a lot of energy in a gallon of gasoline, and it's dangerous in an accident, although car design evolution has helped. Packing more energy into a cubic cm of battery will also add danger, all things being equal. I guess my point is nothing comes free, and beware of "yay more energy". How much energy do we hope to hold in our (cellphone) hand?

We don’t exactly have a major societal problem with flaming phones, despite their density and flammability at the moment.

Battery capacity is just part of story. Much bigger problem is charging and this could not be solved. For example 100kWh requires, at ideal conditions, 100kW for 1 hour, 200kW for 30 min... 1200kW (1.2MW!!!) for 5 min.If we accept long charging times (world will stop cause of this) energies are enormous! Home electric shower is 5 - 7kW, central heating 20 - 30kW and 1 hour charging 100kW! Continuously for single car!

I'm not going to hold my breath on this new tech actually hitting and becoming the revolution (or even evolution) necessary as I always take these kind of announcements with a grain of, well in this case, sand.

I was expecting to have that reaction going in but usually these stories talk about timelines of 5, 10, or 20 years. I'm a little more hopeful about this one considering they're saying it's just a year away.

However, the comment about the pace of battery technology is spot on. Something to be remembered is that the motor design used in EVs has been in use for over a century, and progressive refinement has in that time got the efficiency up from maybe 85% to maybe 95%. The "silicon revolution" happened in such a short timescale that we forget that such events are rare - for instance, the thermal efficiency of gasoline engines has gone from around 20% to around 40% in a century with most of the progress in the last half of that period. I suspect that at the moment EV adoption is entirely about two things: cost reduction of what we already have, and government commitment to the necessary infrastructure to cope with the limitations. A battery 40% lighter (which is initially what it means) is likely to be a vehicle weight improvement of only around 10-15%.

Weight isn’t the blocker for automotive applications; cost is. 20% denser for the same cost means 20% more range for the same price car, or about 5% lower price.

You are making the assumption that 20% denser will cost the same per kilo. That doesn't follow from the article. It is unlikely that a new technology will be cost competitive with an old one for years.

In any case, a 20% range improvement or a price reduction of around 3% (assuming usual overheads) is not a killer feature. On the other hand having charging stations just about everywhere, as with liquid fuel at the moment, would be.

I have a little German tool for smoothing silicone sealant. It consists of a number of alternative pieces of what I suspect is Teflon, each with a different end profile for different joint sizes, but all looking like miniature penises.

It is called, with heavy heavy Germanic humour, a SILI-WILI. And yes, it means exactly what you might think in German slang, though one L is omitted.

However, the comment about the pace of battery technology is spot on. Something to be remembered is that the motor design used in EVs has been in use for over a century, and progressive refinement has in that time got the efficiency up from maybe 85% to maybe 95%. The "silicon revolution" happened in such a short timescale that we forget that such events are rare - for instance, the thermal efficiency of gasoline engines has gone from around 20% to around 40% in a century with most of the progress in the last half of that period. I suspect that at the moment EV adoption is entirely about two things: cost reduction of what we already have, and government commitment to the necessary infrastructure to cope with the limitations. A battery 40% lighter (which is initially what it means) is likely to be a vehicle weight improvement of only around 10-15%.

Weight isn’t the blocker for automotive applications; cost is. 20% denser for the same cost means 20% more range for the same price car, or about 5% lower price.

You are making the assumption that 20% denser will cost the same per kilo. That doesn't follow from the article. It is unlikely that a new technology will be cost competitive with an old one for years.

It's been a while since my EE days, but I seem to remember the anode as the "sink" (+), and the cathode as the source (-).

The nominative roles of the cathode and anode in a rechargeable battery change, depending on whether the battery is charging or discharging. In diodes and other unipolar devices, these roles are fixed.

Researchers have been using cryogenic X-ray and Gamma-ray detectors that have as the sensing element "lithium drifted silicon". What's it been called for about four decades? A SiLi detector, and, yes, it's been pronounced "silly" for all that time.

It's been a while since my EE days, but I seem to remember the anode as the "sink" (+), and the cathode as the source (-).

Depends when you were in school, as I was never exposed to that nomenclature in regards to batteries, but first saw it in circuit design in reference to transistors.

Furthermore, if you were taught 'conventional ' current circuit analysis, the anode is the positive electrode and the cathode is the negative. In 'electron' current convention, the anode is negative and the cathode is positive. Doesn't mattter which one you accept on paper, once you learn to design complex circuits and read schematics, it's like your first language.

I think the previous commenter may have made the point that the directions are reversed for charging. I didn't think about that.